any() matches an expression against every post in a transaction or
account, and returns true if any of them are true. all() tests if all
are true. For example:
ledger -l 'account =~ /Expense/ & any(account =~ /MasterCard/)' reg
This reports every posting affecting an Expense account (regex match),
but only if some other posting in the same transaction affects the
MasterCard account.
Both functions also take a second boolean argument. If it is false, the
"source" posting is not considered. For example:
ledger -l 'any(/x/, false)'
This matches any posting where a *different* posting in the same
transaction contains the letter 'x'.
